The present invention relates to an apparatus and a method for manufacturing tow prepreg and, more particularly, to the control of the amount of resin applied to an original tow of reinforcing fibers (glass fibers, carbon fibers, or the like).
An apparatus for manufacturing tow prepreg impregnates glass fibers or carbon fibers, which serve as an original tow of reinforcing fibers, with resin. As a method to apply resin to the original tow of fibers, a kiss coating method is known. Japanese Laid-Open Patent Publication Nos. 2003-266551 and 2001-40119 each describe an example of a tow prepreg manufacturing apparatus that feeds resin to a rotating roller and adjusts the clearance between the blade and the roller to adjust the applied amount of resin.
Compared to a method of coating an original tow directly with resin, the kiss coating method as a resin application method allows resin to be more uniformly applied to the surface of the original tow and eliminates differences in the applied amount of resin. Further, compared to a bucket process and a dipping process that dips an original tow in resin, foaming of the resin can be reduced and thus can obviate the application of resin that includes bubbles to the original tow.
The original fibers are filament aggregate and thus include many voids that of various sizes. Further, the original tow has a non-uniform thickness and width. It is thus difficult to converge the resin content of the wound tow prepreg (Rc value: applied resin weight/tow prepreg weight) on the desired value just by adjusting the clearance between the roller and the blade. Further, when performing resin impregnation, the temperature of the resin is raised when feeding the resin to the roller. In this case, resin falls from the roller and from a scraper before resin impregnation occurs. This also makes it difficult to keep the Rc value constant.